Error Compensation for Sub-Pixel Displacement Estimation in Cross-Correlation Particle Image Velocimetry（PIV）

Analyzing the cause and the relationship between displacement and bias error in the evaluation of PIV recordings with the correlation-based interrogation algorithm,an error compensation method is presented in this paper.In our proposed algorithm,two correlation planes are obtain first,one with values higher and the another with values smaller than the true sub-pixel displacement.The two correlation planes are then averaged with weights,which is obtained through analyzing the error distribution.Finally,three-point Gaussian interpolation in the new correlation plane provides more accurate sub-pixel displacement.The assessment of synthetic images in the uniform flow,Oseen vortex flow and standard target flow shows that the proposed method can achieve higher evaluation accuracy not only for uniform flows,but also for flows with large velocity magnitude and gradients.